U.S. patent application number 14/075836 was filed with the patent office on 2014-05-15 for display device and driving method thereof.
This patent application is currently assigned to LG DISPLAY CO., LTD.. The applicant listed for this patent is LG DISPLAY CO., LTD.. Invention is credited to MinSung KIM.
Application Number | 20140132559 14/075836 |
Document ID | / |
Family ID | 50681238 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140132559 |
Kind Code |
A1 |
KIM; MinSung |
May 15, 2014 |
DISPLAY DEVICE AND DRIVING METHOD THEREOF
Abstract
Discussed is a display device. The display device includes a
panel in which a self-capacitive touch panel including a plurality
of touch electrodes is built, and a touch sensing unit configured
to, during a touch sensing period in one frame period, supply a
current to the touch electrodes, hold touch voltages of the
respective touch electrodes when an average voltage of the touch
electrodes reaches a predetermined reference voltage, and compare
each of the touch voltages with a slope voltage to determine
whether each of the touch electrodes is touched while the touch
voltages are being held.
Inventors: |
KIM; MinSung; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG DISPLAY CO., LTD. |
SEOUL |
|
KR |
|
|
Assignee: |
LG DISPLAY CO., LTD.
SEOUL
KR
|
Family ID: |
50681238 |
Appl. No.: |
14/075836 |
Filed: |
November 8, 2013 |
Current U.S.
Class: |
345/174 |
Current CPC
Class: |
G06F 3/04164 20190501;
G06F 3/044 20130101; G06F 3/0443 20190501; G06F 3/04166
20190501 |
Class at
Publication: |
345/174 |
International
Class: |
G06F 3/044 20060101
G06F003/044 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 2012 |
KR |
10-2012-0127354 |
Claims
1. A display device comprising: a panel in which a self-capacitive
touch panel comprising a plurality of touch electrodes is built;
and a touch sensing unit configured to, during a touch sensing
period in one frame period, supply a current to the touch
electrodes, hold touch voltages of the respective touch electrodes
when an average voltage of the touch electrodes reaches a
predetermined reference voltage, and compare each of the touch
voltages with a slope voltage to determine whether each of the
touch electrodes is touched while the touch voltages are being
held.
2. The display device of claim 1, wherein the touch sensing unit
comprises: a plurality of comparators configured to supply a
current to each of the touch electrodes according to a current
supply control signal, hold the touch voltage of each of the touch
electrodes according to a holding control signal, and compare the
touch voltage with a slope voltage to generate counting information
while the touch voltage is being held; a controller configured to
transfer the current supply control signal to the comparator when a
timing for supplying the current to the touch electrodes arrives,
transfer the holding control signal to the comparator when a timing
for holding the touch voltage arrives, and transfer the slope
voltage to the comparator together with the holding control signal;
and a touch determiner configured to determine whether each of the
touch electrodes is touched by using the counting information
transferred from the comparators.
3. The display device of claim 2, wherein each of the comparators
comprises: a converter configured to hold the touch voltage of a
corresponding touch electrode according to the holding control
signal, count until the touch voltage and the slope voltage have
the same value while the touch voltage is being held, convert the
counted value into the counting information, and output the
counting information; and a charge pump configured to supply or not
to supply a current to the touch electrode according to the current
supply control signal.
4. The display device of claim 4, wherein the converter comprises:
at least one or more counting units configured to hold the touch
voltage of the touch electrode according to the holding control
signal, and count until the touch voltage and the slope voltage
have the same value while the touch voltage is being held; and an
output unit configured to convert at least one or more counted
values into the counting information, and output the counting
information to the touch determiner.
5. The display device of claim 2, wherein the controller comprises:
a control signal generating unit configured to, when an average
voltage of the touch electrodes calculated by using the touch
voltages detected from the respective touch electrodes reaches the
predetermined reference voltage, transfer the current supply
control signal and the holding control signal to the comparators;
and a slope voltage generating unit configured to, when the holding
control signal is applied to the comparators, applies the slope
voltage to the comparators.
6. A method of driving a display device, the method comprising:
during a touch sensing period in one frame period, supplying a
current to a plurality of touch electrodes, and when an average
voltage of the touch electrodes reaches a predetermined reference
voltage, holding touch voltages of the respective touch electrodes;
and comparing each of the touch voltages with a slope voltage to
determine whether each of the touch electrodes is touched while the
touch voltages are being held.
7. The method of claim 6, wherein the supplying of the current and
the holding of the touch voltages comprises: supplying a current to
each of the touch electrodes according to a current supply control
signal; and holding the touch voltage of each of the touch
electrodes according to a holding control signal.
8. The method of claim 7, wherein the holding of touch voltages
comprises: when a timing for holding the touch voltage arrives,
generating the holding control signal; preventing the current from
being supplied to the touch electrodes according to the holding
control signal; and generating the slope voltage together with the
holding control signal.
9. The method of claim 8, wherein the determining of whether each
of the touch electrodes is touched comprises: counting until the
touch voltages and the slope voltage have the same value while the
touch voltages is being held; converting the counted value into the
counting information; and determining whether each of the touch
electrodes is touched by using the counting information.
10. The method of claim 6, wherein the supplying of the current and
the holding of the touch voltages comprise: supplying the current
to the touch electrodes; when an average voltage of the touch
electrodes calculated by using the touch voltages detected from the
respective touch electrodes reaches the predetermined reference
voltage, stopping the supply of the current; and when the average
voltage of the touch electrodes reaches the predetermined reference
voltage, holding the touch voltages, and then generating the slope
voltage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the Korean Patent
Application No. 10-2012-0127354 filed on Nov. 12, 2012, which is
hereby incorporated by reference as if fully set forth herein.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a display device, and more
particularly, to a display device with a built-in self-capacitive
touch panel.
[0004] 2. Discussion of the Related Art
[0005] With the advance of various portable electronic devices such
as mobile terminals and notebook computers, the demand for flat
panel display devices applied to the portable electronic devices is
increasing.
[0006] In such FPD devices, the application fields of the LCD
devices are being continuously expanded because the LCD devices are
easily manufactured due to the advance of manufacturing technology
and realize a drivability of a driver, a high-quality image, and a
large screen.
[0007] Instead of an input device such as a mouse or a keyboard
which is conventionally applied to LCD devices, a touch screen that
enables a user to directly input information with a finger or a pen
is recently applied as an input device to LCD devices.
[0008] As types in which a touch panel is provided at a liquid
crystal panel, there are an on-cell type, an in-cell type, and a
hybrid in-cell type. LCD devices using the in-cell type or the
hybrid in-cell type are called LCD devices with a built-in touch
panel.
[0009] FIG. 1 is an exemplary diagram illustrating a configuration
of a related art LCD device, and FIG. 2 is an exemplary diagram
showing a timing at which a common voltage and a driving pulse are
applied to a touch electrode in the related art LCD device.
[0010] The related art LCD device with a built-in touch panel, as
illustrated in FIG. 1, includes a liquid crystal panel 10 with a
built-in touch panel 60 and a touch sensing unit 30 for driving the
touch panel 60. A method of driving the touch panel 60 includes a
resistive type and a capacitive type. The capacitive type is
categorized into a self-capacitive type and a mutual type.
[0011] In the related art LCD device using the self-capacitive type
of the types, as illustrated in FIG. 1, a touch electrode line 62
is separately extended from each of a plurality of touch electrodes
61, and "q.times.p=n" number of sensors 31 are needed in
consideration of the number "q" of widthwise touch electrodes and
the number "p" of lengthwise touch electrodes. When the number of
sensors 31 is small, the touch sensing unit 30 itself may be
configured as one integrated circuit (IC), and when many sensors
are needed, a plurality of ICs (touch ICs) configured with a
plurality of the sensors 31 may configure the touch sensing unit
30.
[0012] In the above-described LCD device with the built-in
self-capacitive touch panel, since a touch electrode receiving a
driving pulse is used as a common electrode, an output of an image
and touch sensing cannot simultaneously be performed. Therefore, as
shown in FIG. 2, one frame period determined by a vertical sync
signal Vsync is divided into a display period and a touch sensing
period.
[0013] Each of the sensors 31 applies ten or more driving pulses to
the touch electrode 61 during the touch sensing period, and
analyzes a sensing signal received from the touch electrode to
determine whether a corresponding touch electrode is touched.
[0014] Generally, in the self-capacitive type, determining whether
there is a touch uses charging or discharging of the driving pulse.
That is, in the self-capacitive type, a touch is detected by using
a voltage slope change caused by a change in a capacitance value
which occurs between when there is a touch and when there is no
touch
[0015] FIG. 3 is a graph for describing a method of determining a
touch in a related art display device using the self-capacitive
type.
[0016] In the self-capacitive type, a relaxation oscillation type
is being widely used.
[0017] In the relaxation oscillation type, a sensing time is
decided based on a self-capacitance value and the number of
charging and discharging.
[0018] In the relaxation oscillation type, a time decided based on
a self-capacitance value is counted with a clock generated from a
reference oscillator.
[0019] In the relaxation oscillation type, a digital code value can
be obtained by counting a decided time with a clock generated from
the reference oscillator.
[0020] However, the relaxation oscillation type has a problem that
it is difficult to determine whether there is a touch in an in-cell
type touch panel.
[0021] The relaxation oscillation type is a very useful structure
in a single self-capacitive type. However, a parasitic capacitance
is generated between self-capacitances in the in-cell touch panel,
and thus, when the same voltage is not provided, the parasitic
capacitance value is greatly changed. For this reason, crosstalk
occurs, and a unique value of the self-capacitance is changed,
whereby it becomes difficult to determine whether there is a
touch.
[0022] To provide an additional description, in the related art
relaxation oscillation type, as shown in FIG. 3, a current is
supplied to each of a plurality of touch electrodes to increase a
voltage of each touch electrode to a predetermined touch voltage,
and then whether there is a touch is determined by counting a time
when the touch voltage is again dropped. The time when the touch
voltage is dropped varies according to whether there is a touch,
and thus, whether there is a touch may be determined by using a
time difference. The above-described operation may be repeated
several times for increasing the time difference. In FIG. 3, a
method that counts the time when the operation is repeated four
times is illustrated.
[0023] However, when a touch is made in plurality in a plurality of
touch electrodes or a touch is made in one of a plurality of touch
electrodes, touch electrodes adjacent to a touch electrode in which
a touch occurs are affected by a capacitance change of the touch
electrode in which the touch occurs. For this reason, an abnormal
touch can be detected even in the adjacent touch electrodes.
SUMMARY
[0024] Accordingly, the present invention is directed to providing
a display device and a driving method thereof that substantially
obviate one or more problems due to limitations and disadvantages
of the related art.
[0025] An aspect of the present invention is directed to providing
a display device and a driving method thereof which, when an
average voltage of touch electrodes reaches a predetermined
reference voltage by supplying a current to the touch electrodes,
can determine whether the touch electrodes are touched while
respective touch voltages of the touch electrodes are being
held.
[0026] Additional advantages and features of the invention will be
set forth in part in the description which follows and in part will
become apparent to those having ordinary skill in the art upon
examination of the following or may be learned from practice of the
invention. The objectives and other advantages of the invention may
be realized and attained by the structure particularly pointed out
in the written description and claims hereof as well as the
appended drawings.
[0027] To achieve these and other advantages and in accordance with
the purpose of the invention, as embodied and broadly described
herein, there is provided a display device including: a panel in
which a self-capacitive touch panel including a plurality of touch
electrodes is built; and a touch sensing unit configured to, during
a touch sensing period in one frame period, supply a current to the
touch electrodes, hold touch voltages of the respective touch
electrodes when an average voltage of the touch electrodes reaches
a predetermined reference voltage, and compare each of the touch
voltages with a slope voltage to determine whether each of the
touch electrodes is touched while the touch voltages are being
held.
[0028] In another aspect of the present invention, there is
provided a method of driving a display device, including: during a
touch sensing period in one frame period, supplying a current to a
plurality of touch electrodes, and when an average voltage of the
touch electrodes reaches a predetermined reference voltage, holding
touch voltages of the respective touch electrodes; and comparing
each of the touch voltages with a slope voltage to determine
whether each of the touch electrodes is touched while the touch
voltages are being held.
[0029] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0031] FIG. 1 is an exemplary diagram illustrating a configuration
of a related art LCD device;
[0032] FIG. 2 is an exemplary diagram showing a timing at which a
common voltage and a driving pulse are applied to a touch electrode
in the related art LCD device;
[0033] FIG. 3 is a graph for describing a method of determining a
touch in a related art display device using a self-capacitive
type;
[0034] FIG. 4 is an exemplary diagram schematically illustrating a
configuration of a display device according to the present
invention;
[0035] FIG. 5 is an exemplary diagram illustrating an internal
configuration of a touch sensing unit applied to a display device
according to a first embodiment of the present invention;
[0036] FIG. 6 is a timing diagram showing a touch voltage and a
slope voltage applied to the display device according to the first
embodiment of the present invention;
[0037] FIG. 7 is an exemplary diagram illustrating an internal
configuration of a touch sensing unit applied to a display device
according to a second embodiment of the present invention; and
[0038] FIG. 8 is a timing diagram showing a touch voltage and a
slope voltage applied to the display device according to the second
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0039] Reference will now be made in detail to the exemplary
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0040] Hereinafter, embodiments of the present invention will be
described in detail with reference to the accompanying drawings. In
the following description, for convenience of description, an LCD
device will be described as an example of the present invention,
but the present invention is not limited thereto. That is, the
present invention may be applied to various display devices that
display an image by using a common electrode and a common
voltage.
[0041] FIG. 4 is an exemplary diagram schematically illustrating a
configuration of a display device according to the present
invention.
[0042] The present invention relates to a hybrid in-cell or in-cell
type display device. In a method of driving a touch panel in the
display device with the built-in touch panel, there are a resistive
type and a capacitive type.
[0043] The capacitive type may be again categorized into a
self-capacitive type and a mutual type. The present invention uses
the self-capacitive type.
[0044] An LCD device according to the present invention, as
illustrated in FIG. 4, includes: a panel 100 in which a plurality
of pixels defined by intersections between a plurality of data
lines and a plurality of gate lines are formed; a plurality of
touch electrodes 510 that are built into the panel 100; a
self-capacitive touch panel 500 in which a plurality of touch
electrode lines 520 respectively connected to the plurality of
touch electrodes are formed; a touch sensing unit 600 that, during
a touch sensing period in one frame period, supplies a current to
the touch electrodes, holds touch voltages of the respective touch
electrodes when an average voltage of the touch electrodes reaches
a predetermined reference voltage, and compares each of the touch
voltages with a slope voltage to determine whether each of the
touch electrodes is touched while the touch voltages are being
held; and a driver 400 that outputs image signals to the respective
data lines formed in the panel 100, outputs a scan signal to the
gate lines, and outputs a common voltage to the touch
electrodes.
[0045] The self-capacitive touch panel 500 with the plurality of
touch electrodes 510 formed therein is built into the panel
100.
[0046] The panel 100 may be changed depending on the kind of
display device, and particularly, when the display device is an LCD
device, the panel 100 may be a liquid crystal panel in which a
liquid crystal layer is formed between two glass substrates.
[0047] In this case, a plurality of data lines, a plurality of gate
lines intersecting the plurality of data lines, a plurality of thin
film transistors (TFTs) respectively formed in a plurality of
intersection areas between the plurality of gate lines and the
plurality of data lines, a plurality of pixel electrodes for
charging a data voltage into a corresponding pixel, and the
plurality of touch electrodes 510 for driving liquid crystal
charged into the liquid crystal layer together with a corresponding
pixel electrode are provided at a lower glass substrate of the
panel 100. Here, a plurality of the pixels are arranged in a matrix
type by an intersection structure of the data lines and the gate
lines. A plurality of black matrixes (BM) and a plurality of color
filters are formed at an upper glass substrate of the panel
100.
[0048] The present invention relates to a display device with a
built-in touch panel in which the touch electrodes 510 configuring
the touch panel 500 are included in the panel 100 as described
above.
[0049] The touch panel 500 performs a function of determining
whether there is a user's touch, and particularly, the touch panel
500 applied to the present invention uses the capacitive type using
the self-capacitive type. The touch panel 500 includes the
plurality of touch electrodes 510 and the plurality of touch
electrode lines 520.
[0050] The plurality of touch electrodes 510 may be provided all
over the plurality of pixels formed in the panel 100. The touch
electrodes 510 generate respective touch voltages that increase to
a predetermined average voltage with a current applied from the
touch sensing unit 600 to enable determination of whether there is
a touch, during the touch sensing period. During a display period,
the touch electrodes 510 drive the liquid crystal together with a
corresponding pixel electrode formed in a corresponding pixel.
[0051] Each of the plurality of touch electrode lines 520 is
connected to a corresponding touch electrode 510, and a distal end
thereof is connected to the touch sensing unit 600.
[0052] The touch panel 500 applied to the present invention, as
described above, uses the capacitive type, and is built into the
panel 100. That is, the touch electrodes 510 of the touch panel 500
applied to the present invention acts as a common electrode for
driving the liquid crystal together with a corresponding pixel
electrode, and are provided in the panel 100.
[0053] The driver 400 may be configured with a gate driver for
controlling signals inputted to the respective gate lines, a data
driver for controlling signals inputted to the respective data
lines, and a timing controller for controlling the gate driver and
the data driver. The gate driver, data driver, and timing
controller configuring the driver 400 may be configured as one
integrated circuit (IC) as illustrated in FIG. 4, or may be
provided separately.
[0054] The timing controller receives a timing signal, including a
data enable signal (DE), a dot clock (CLK), etc., from an external
system to generate control signals (GCS and DCS) for controlling an
operation timing of each of the data driver and gate driver. Also,
the timing controller realigns video data inputted from the
external system to output the realigned image data to the data
driver.
[0055] The timing controller may control the data driver and the
gate driver. Further, the timing controller may generate a control
signal for controlling an input/output operation timing of the
touch sensing unit 600 and control signals for enabling the touch
sensing unit 600 to apply one of the common voltage and the driving
pulse to the touch electrodes, and transfer the control signals to
the touch sensing unit 600.
[0056] That is, the common voltage outputted to the touch
electrodes 510 may be generated by a common voltage generator and
outputted through the driver 400, or may be outputted through the
touch sensing unit 600 receiving the control signal from the driver
400. Also, the driving pulse may be outputted through the touch
sensing unit 600 receiving the control signal from the driver
400.
[0057] The data driver converts the image data, inputted from the
timing controller, into analog data voltages, and supplies the data
voltages for one horizontal line to the respective data lines at
every one horizontal period in which the scan signal is supplied to
the gate lines.
[0058] The gate driver shifts a gate start pulse (GSP) transferred
from the timing controller according to a gate shift clock (GSC) to
sequentially supply a gate-on voltage (Von) to the gate lines (GL1
to GLn).
[0059] Finally, as described above, during the touch sensing period
in one frame period, the touch sensing unit 600 supplies a current
to the touch electrodes, holds touch voltages of the respective
touch electrodes when an average voltage of the touch electrodes
reaches the predetermined reference voltage, and compares each of
the touch voltages with the slope voltage to determine whether each
of the touch electrodes is touched while the touch voltages are
being held.
[0060] That is, during the touch sensing period in one frame
period, the touch sensing unit 600 supplies a current to the touch
electrodes 510 until an average voltage of the touch electrodes 510
reaches the predetermined reference voltage. When the average
voltage reaches the predetermined reference voltage, the touch
sensing unit 600 holds the touch voltages of the respective touch
electrodes, and compares each of the touch voltages with the slope
voltage to determine whether each of the touch electrodes is
touched while the touch voltages are being held.
[0061] To this end, as illustrated in FIG. 4, the touch sensing
unit 600 includes a plurality of comparators 610, a controller 620,
and a touch determiner 630.
[0062] A detailed function and operation method of the touch
sensing unit 600 will be described in detail with reference to
FIGS. 4 to 8.
[0063] FIG. 5 is an exemplary diagram illustrating an internal
configuration of a touch sensing unit 600 applied to a display
device according to a first embodiment of the present invention,
and FIG. 6 is a timing diagram showing a touch voltage and a slope
voltage applied to the display device according to the first
embodiment of the present invention. FIG. 7 is an exemplary diagram
illustrating an internal configuration of a touch sensing unit 600
applied to a display device according to a second embodiment of the
present invention, and FIG. 8 is a timing diagram showing a touch
voltage and a slope voltage applied to the display device according
to the second embodiment of the present invention.
[0064] The display device according to the present invention
applies the common voltage to the touch electrodes 510 during the
display period in one frame, and determines whether a touch occurs
in the touch panel 500 by using the touch electrodes 510 during the
touch sensing period in the one frame. A method, in which the
common voltage is applied to the touch electrodes 510, may be
variously implemented depending on a configuration and function of
each of the driver 400 and touch sensing unit 630. Thus, the
following description will focus on a function of determining
whether a touch occurs in the touch panel 500 during the touch
sensing period among functions of the display device according to
the first embodiment of the present invention.
[0065] Hereinafter, in the configuration and function of the touch
sensing unit 600 determining whether there is a touch,
particularly, the configuration and function for determining
whether there is the touch will be described in detail.
[0066] The touch sensing unit 600 applied to the display device
according to the present invention, as illustrated in FIG. 5,
includes: a plurality of comparators 610 that supply a current to
each of the touch electrodes 510 according to a current supply
control signal, hold a touch voltage Vtouch of each of the touch
electrodes 510 according to a holding control signal, and compare
the touch voltage Vtouch with a slope voltage Vslope to generate
counting information while the touch voltage is being held; a
controller 620 that transfers the current supply control signal to
the comparator 610 when a timing for supplying the current to the
touch electrodes 510 arrives, transfers the holding control signal
to the comparator 610 when a timing for holding the touch voltage
Vtouch arrives, and transfers the slope voltage Vslope to the
comparator 610 together with the holding control signal; and a
touch determiner 630 that determines whether each of the touch
electrodes 510 is touched by using the counting information
transferred from the comparators 610.
[0067] The comparators 610 are connected to the touch electrodes
510 in one-to-one correspondence relationship. Each of the
comparators 610 includes: a converter 619 that holds the touch
voltage Vtouch of a corresponding touch electrode 510 according to
the holding control signal, counts until the touch voltage Vtouch
and the slope voltage Vslope have the same value while the touch
voltage Vtouch is being held, converts the counted value into the
counting information, and outputs the counting information; and a
charge pump 611 that supplies or does not supply a current to the
touch electrode 501 according to the current supply control
signal.
[0068] The converter 619 includes: at least one or more counting
units 618a and 618b that hold the touch voltage Vtouch of the touch
electrode 510 according to the holding control signal, and count
until the touch voltage Vtouch and the slope voltage Vslope have
the same value while the touch voltage Vtouch is being held; and an
output unit 614 that converts at least one or more counted values
into the counting information, and outputs the counting information
to the touch determiner 630.
[0069] Each of the at least one counting units 618a and 618b
includes: a holder (S/H) 612 that holds the touch voltage Vtouch
according to the holding control signal; and a comparator 613 that,
while the touch voltage Vtouch is being held, compares the touch
voltage Vtouch with the slope voltage Vslope transferred from the
controller 620, and counts until the touch voltage Vtouch and the
slope voltage Vslope have the same value.
[0070] In the display device according to the first embodiment of
the present invention, as illustrated in FIG. 5, only one counting
unit 618a is provided in the converter 619. In this case, as shown
in FIG. 6, a section in which the touch voltage Vtouch rises does
not overlap a section in which the slope voltage Vslope falls.
[0071] In the display device according to the second embodiment of
the present invention, as illustrated in FIG. 7, two counting units
618a and 618b are provided in the converter 619. In this case, as
shown in FIG. 8, the section in which the touch voltage Vtouch
rises may overlap the section in which the slope voltage Vslope
falls.
[0072] In addition to the first and second embodiments, the
converter 619 applied to the display device according to the
present invention may include various number of counting units.
[0073] As the number of counting units increases, sensing may be
more performed, and thus, whether there is a touch can be
determined more accurately.
[0074] The output unit 614 converts the value counted by the
comparator 613 into the counting information, and outputs the
counting information to the touch determiner 630. That is, a count
value generated by the comparator 613 is converted into digital
information, which is transferred to the touch determiner 630.
[0075] The charge pump 611 supplies or does not supply a current to
the touch electrode 501 according to the current supply control
signal. That is, as shown in FIGS. 6 and 8, the charge pump 611
supplies the current to the touch electrode 510 to increase the
touch voltage Vtouch of the touch electrode 510 in a charge mode
during the touch sensing period.
[0076] The touch determiner 630 determines whether the touch
electrodes 510 are touched by using the counting information
transferred through the output unit 614 of each of the comparators
610.
[0077] Finally, when a timing for supplying the current to the
touch electrode 510 arrives, the controller 620 transfers the
current supply control signal to the comparator 610, and when a
timing for holding the touch voltage Vtouch arrives, the controller
620 transfers the holding control signal to the comparator 610, and
transfers the slope voltage Vslope to the comparator 610 together
with the holding control signal.
[0078] To this end, the controller 620 includes: a control signal
generating unit 621 that, when an average voltage of the touch
electrodes calculated by using the touch voltages Vtouch detected
from the respective touch electrodes 510 reaches the predetermined
reference voltage Vref, transfers the current supply control signal
and the holding control signal to the comparators 610; and a slope
voltage generating unit 622 that, when the holding control signal
is applied to the comparators 610, applies the slope voltage Vslope
to the comparators 610.
[0079] The control signal generating unit 621 includes: an average
voltage calculator 621a that calculates an average voltage of the
touch electrodes 510 by using the touch voltages Vtouch detected
from the respective touch electrodes 510; a digital-to-analog
converter (DAC) 621d that stores information on the reference
voltage Vref; a driving unit 621c that controls driving of the DAC
621d; a reference voltage comparator 621b that compares the average
voltage with the reference voltage to determine whether the average
voltage is the same as the reference voltage; a selector 621e that,
when the average voltage is the same as the reference voltage as
the compared result by the reference voltage comparator 621b,
selects and generates a specific signal; a shift register 621f that
sequentially shifts the signal generated from the selector 621e;
and a timing generator 621g that generates the current supply
control signal and the holding control signal according to the
signal transferred through the shift register 621f, and transfers
the current supply control signal and the holding control signal to
the comparators 610.
[0080] The slope voltage generating unit 622 includes: a gain
buffer 622a that prepares to generate the slope voltage when the
average voltage increases to a certain level; and a slope voltage
generator 622b that generates the slope voltage Vslope according to
the signal transferred from the gain buffer 622a.
[0081] Hereinafter, a method of driving the display device
according to the present invention will be described in detail with
reference to FIGS. 6 and 7. Here, as described above, in the second
embodiment of the present invention illustrated in FIGS. 7 and 8,
the two counting units 618a and 618b are provided in the comparator
610. Therefore, except that a partial section of the slope voltage
Vslope overlaps a partial section of the touch voltage Vtouch, the
second embodiment of the present invention is the same as the first
embodiment of the present invention illustrated in FIGS. 5 and 6.
Thus, the first embodiment of the present invention will be
described below.
[0082] First, during the touch sensing period in one frame, the
comparator 610 supplies a current to the touch electrode 510
according to the current supply control signal transferred from the
controller 620. Therefore, as shown in the charge mode of FIG. 6,
the touch voltages Vtouch of the touch electrode 510 rise.
[0083] Before supplying a current to the touch electrodes 510, an
operation of removing a current remaining in the touch electrodes
510 may be performed. That is, in a reset mode shown in FIG. 6, by
applying a certain voltage to each initial channel (a touch
electrode), an electric charge of the touch electrode is set to
0.
[0084] The average voltage calculator 621a of the control signal
generating unit 621 configuring the controller 620 calculates an
average voltage of the touch voltages by using the touch voltages
Vtouch transferred from the respective touch electrodes 510.
[0085] The control signal generating unit 621 of the controller 620
determines whether the average voltage of the touch voltages is the
same as the predetermined reference voltage Vref.
[0086] When it is determined that the average voltage is the same
as the predetermined reference voltage, the controller 620
generates the current supply control signal for preventing the
supply of the holding control signal and the current, and transfers
the current supply control signal to the comparator 610.
[0087] The charge pump 611 receiving the current supply control
signal prevents the supply of the current, and the holder 612 holds
the touch voltage Vtouch of the touch electrode 510 in a voltage
hold mode shown in FIG. 6. Therefore, the touch voltages Vtouch
which increase the respective touch electrodes are maintained at a
constant level.
[0088] The controller 620 transfers the slope voltage Vslope to the
comparators 610.
[0089] The converter 619 counts a period until the touch voltage
Vtouch becomes equal to the slope voltage Vslope, in a compare mode
shown in FIG. 6. The counted value is converted into counting
information, which is transferred to the touch determiner 630.
[0090] That is, although the current is applied to the touch
electrodes 510 up to the average voltage of the touch voltages, a
level of the touch voltage of each touch electrode 510 may be
changed according to whether each touch electrode 510 is touched.
For example, as shown in FIG. 6, immediately when the average
voltage reaches the reference voltage Vref, the touch voltages of
the respective touch electrodes 510 have different values according
to whether there is a touch.
[0091] Therefore, times respectively taken until the touch voltages
Vtouch become equal to the slope voltage Vslope differ as referred
to as a, b, c, and d in the compare mode of FIG. 6.
[0092] Finally, the touch determiner 630 determines whether there
is a touch for each touch electrode 510 by using the counting
information transferred from the comparators 610.
[0093] The above-described details will be summarized as
follows.
[0094] The present invention injects a certain electric charge into
each channel (a node connected to the touch electrode) of the
in-cell type touch panel having the self-capacitive type to
calculate an average voltage of the touch voltages generated from
the respective touch electrodes, and determines whether each of the
touch electrodes is touched according to a difference between times
taken until the touch voltages become equal to the slope voltage.
To this end, the present invention performs the following
functions.
[0095] First, in the reset mode, the present invention sets an
electric charge of each touch electrode to 0 by applying a certain
voltage to each initial channel (the touch electrode).
[0096] Second, in the charge mode, the present invention injects a
certain current into the touch electrodes having an electric charge
of 0 by using the charge pump 611 to linearly increase the touch
voltages.
[0097] Third, in the voltage hold mode, the present invention holds
the touch voltages at a time when the average voltage of touch
voltages, which linearly increase as a current increases, reaches
the reference voltage Vref.
[0098] Fourth, in the compare mode, the present invention compares
the held touch voltages with the slope voltage having a slope to
output a change value based on a touch as a digital code.
[0099] Particularly, as illustrated in FIGS. 7 and 8, a converter
619 of one comparator 610 includes two counting units 618a and 618b
that include a holder 612 and a comparator 613, and the elements
may operate at an odd time and an even time. The operation is
called a pipe line operation. According to such an operation, a
touch sensing function for touch sensing is performed together for
a certain time, and thus, a loss time can be reduced.
[0100] The present invention injects an electric charge into the
touch electrodes 510 for a certain time, compares the touch
voltages and the slope voltage, and discharges the touch voltages.
Accordingly, in the in-cell touch panel having the self-capacitive
type, a mutual parasitic capacitance between the touch electrodes
can be removed.
[0101] According to the present invention, since the mutual
parasitic capacitance is removed, voltage distortion caused by
crosstalk does not occur.
[0102] Since the present invention compares the touch voltages
(which have linearly increased in the charge mode) with the slope
voltage having a certain slope, a touch detection function can be
enhanced according to a slope of the slope voltage.
[0103] According to the present invention, the touch voltages in
the respective touch electrodes 510 are compared with the slope
voltage after being short-circuited from the outside in the compare
mode, an external noise is not inputted. Accordingly, the touch
detection function can be enhanced.
[0104] In the present invention, as illustrated in FIGS. 7 and 8,
since a pipe line sensing structure cannot be applied to the
present invention, sensing can be performed without time being
lost.
[0105] Since a certain electric charge is continuously injected
into the touch electrodes until the average voltage of touch
voltages of the touch electrodes (channels) reaches the reference
voltage, the present invention can better prevent a touch sensing
miss caused by an external noise than the related art method that
injects an electric charge for a certain time.
[0106] According to the present invention, an immunity to a high
frequency noise or a peak noise is enhanced for a certain charge
injection time due to a response time of the average voltage
calculator 621a generating the average voltage, and a
signal-to-noise ratio (SNR) can be enhanced.
[0107] As described above, when an average voltage of touch
electrodes reaches a predetermined reference voltage by supplying a
current to the touch electrodes, the present invention determines
whether the touch electrodes are touched while respective touch
voltages of the touch electrodes are being held, thus decreasing
respective influences of adjacent touch electrodes on the touch
electrodes.
[0108] That is, since the present invention determines whether the
touch electrodes are touched when touch voltages of all the touch
electrodes have increased to an average voltage, a noise component
applied to each of the touch electrodes is reduced, and thus a
touch sensitivity can be enhanced.
[0109] Generally, when a self-capacitance value is equal to or
greater than 50 pF, an amount of capacitance changed by a touch is
0.5 pF to 0.9 pF. Therefore, the present invention can change a
data value, based on a fine change in a capacitance, to a high
value. Also, by accumulating the data value, the present invention
can determine a fine capacitance change based on whether there is a
touch.
[0110] Moreover, the present invention uses the sensing method that
generates touch voltages of all the touch electrodes as an average
voltage, and thus can enhance an SNR.
[0111] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *